Video 8:50
Possible link between lead and violent crime.

John StewartUpdated
Tue 9 Apr 2013, 11:46 PM AEST

The preliminary findings of the first Australian study of potential links between lead exposure and violent crime shows that suburbs exposed to high lead pollution levels also experience high assault rates.

Transcript

EMMA ALBERICI, PRESENTER: It's long been known that lead poisoning damages the human brain but scientists are now examining the heavy metals long term effects on human behaviour. A scientist has begun the first study of potential links between exposure to lead in Australian children and violent crime later in life. The study's preliminary findings show that suburbs exposed to high lead pollution levels also experience high assault rates. This report from John Stewart, and Candice Talberg was the producer.

JOHN STEWART, REPORTER: Chad Hinds suffers from bipolar disorder and memory loss. With medication he's able to work and look after his eight month old son. Chad grew up in the NSW town of Boolaroo next door to the town's lead and zinc smelter. As a child, he suffered from Asthma and lived with the smell of the smelter day and night.

CHAD HINDS, LEAD POISONING VICTIM: It was just like a foul, off, yuck taste.

JOHN STEWART: In primary school he struggled to learn and started falling behind.

CHAD HINDS: Reading was the one I didn't, you know, cause, every now and then they get the whole class reading, you know, and I'd be like "oh no," I was worried about reading because I couldn't read.

JOHN STEWART: Chad grew up in this house in Boolaroo just 300 metres from the smelter. His parents say that he spent a lot of time outdoors playing in the dirt. The area had such high lead levels that the smelter operators had to buy most of the houses in this street.

PAT HINDS, CHAD'S FATHER: We got not actually the soil but the dust in the ceilings above our front door we got tested and that was just off the scale, it was.

JOHN STEWART: As Chad became a teenager his behaviour continued to deteriorate.

CHAD HINDS: I was just out of control. Mum would put AVOs on me because I was just a loose cannon.

PAT HINDS: And very aggressive, you know, like a mood swing type of thing, you know.

JOHN STEWART: Today Australian health authorities aim to keep lead levels in children below 10 micrograms per decilitre. In 1991, children at Boolaroo primary school were given a blood lead test. 84 per cent of children at the school produced levels above 10.

THERESA GORDON, NO LEAD GROUP For Chad, 300 metres way from a main smelter, lovely, happy, lively, energetic boy. He would have no doubt suffered high lead levels and in fact he did. From memory Chad had a blood level of 29 micrograms per decilitre at the age of six or 7, I think that was.

JOHN STEWART: Chad later went to jail for breaching an apprehended violence order. His spiral into violent behaviour may have had many causes. In the United States, scientists are increasingly looking at lead as a potential cause of impulsive crime.

SAMMY ZAHRAN, DEMOGRAPHER AT COLORADO STATE UNIVERSITY: Neuroscientific evidence showing that adults lead poisoned as children, have volumetric loss in the prefrontal cortex, in the anterior cingulate cortex, regions of the brain that govern mood regulation, executive judgment, impulse control.

JOHN STEWART: Professor Mark Taylor has begun Australia's first study of suburbs with high lead air pollution levels and local crime rates.

MARK TAYLOR, ENVIRONMENTAL SCIENTIST AT MACQUARIE UNIVERSITY: So what we've done, we've got to the EPA and we've extracted lead in air information as far back as we can possibly find it which is to the early '70s. And then we've managed to get the criminal information from BOCSAR, the NSW Justice and Crime Bureau, which is very robust and that's collected robustly and reliably from '95 onwards and then we've applied that relationship.

JOHN STEWART: The research indicates that 20 year time lag between the peaks in lead air pollution and peaks in the rates of assault.

MARK TAYLOR: So the locations that we're looking at are, for example, Sydney, Rozelle, there's a place in Earlwood which is in Canterbury, there's Boolaroo which is the site of the old Cockle Creek smelter, Port Kembla as well so we've been able to extract reasonably good records for those sites.

JOHN STEWART: The initial results have produced a strong correlation between peaks in air pollution during the 1970s and '80s, before lead in petrol was banned, and high assault rates in the same locations 20 years later. At Boolaroo lead air pollution from the smelter peaked in 1988. The local assault rate peaked 21 years later in 2009. At Earlwood in Sydney, lead air pollution from leaded petrol peaked in 1982, the assault rate peaked in 2002. At Port Kembla, south of Sydney, lead air pollution from heavy industry peaked in 1979, the assault rate peaked in 1999. At Lane Cove in Sydney, lead air pollution from leaded petrol peaked in 1978, the assault rate peaked in 1999.

MARK TAYLOR: Well, we're not saying it's a one to one relationship. What we're saying is that lead exposure is associated with violent activity. It predisposes those children, it puts them on a trajectory where they may, along with other factors in their life, it may then predispose them to violent activity later on in life.

JOHN STEWART: Last year demographer Sammy Zahran completed a similar study exploring links between six American cities with high lead pollution and assault rates. He found a consistent 20 year time gap between lead pollution and violent crime.

SAMMY ZAHRAN: When lead emissions were high 22 years prior you're going to have a generation of young adults that are sort of ageing into the age crime curve exposed to higher levels in the past.

JOHN STEWART: Critics of population studies say the research is too broad.

WAYNE HALL, UNIVERSITY OF QUEENSLAND PROFESSOR: You can't be sure that the people who might be experiencing lead exposure are the same people who are involved in committing crimes. So ideally, you need information at the individual level showing that for individuals there's a connection between lead exposure and likelihood of engaging in crime.

JOHN STEWART: But Professor Taylor says the impacts of exposure to lead in Australian children cannot be ignored.

MARK TAYLOR: We know that crimes associated with lower IQ and we're trying to look at the relationship between the two. We're not saying that lead is the only driver of that relationship, we're saying in the Australian context that's never really been considered.

WAYNE HALL: It's certainly a hypothesis that deserves to be taken seriously and further investigated. It's probably a bit early to be drawing strong conclusions that the relationship is causal.

JOHN STEWART: In the United States lead is increasingly being viewed as a long term public health risk.

SAMMY ZAHRAN: I think the true cost of lead we're only beginning to fully calculate. So this research into violence is only one of a long string of negative outcomes that epidemiologists and economists have noted. And so as we begin to tabulate this loss I think it will be - it will one day be understood as one of the greatest sort of public health mistakes that we've committed.

JOHN STEWART: The smelter at Boolaroo closed 10 years ago. Chad Hinds believes that lead has affected his mental health. He acknowledges that other things have gone wrong with his life but he's convinced that he's paid a high price for growing up next door to a lead smelter.

CHAD HINDS: My memory's hopeless now. I can't remember what I done three days ago, you know what I mean, even though I knew I went to work but what I done during the day I just can't remember. That's affected me like that, you know. Yeah, it's definitely affected me, you know, it's catching up with me as I get older.